Grimace was originally called Evil Grimace when the McDonald's character first appeared in 1971.
The early character was very different from the friendly purple figure familiar from later McDonald's advertising. Evil Grimace was presented as a villainous character with multiple arms who could take milkshakes. The character's role connected directly to McDonald's drinks and gave the advertising stories a mischievous antagonist.
McDonald's later simplified the character and changed the personality. Grimace became a large, purple, good-natured companion rather than a threatening milkshake thief. That transformation helped make the character more suitable for family-oriented advertising and long-term recognition.
People often remember only the later version and assume Grimace always had the same design. The original name is therefore a useful branding-history detail: Evil Grimace identifies the early 1971 concept, while the familiar friendly Grimace belongs to the character's later development.